Magnetic Field Sensor

A sensor comprising:

• a light trapping diamond nitrogen vacancy doped layer having upper and lower faces;
• a dielectric coating disposed over a portion of the lower face of the diamond layer;
• a microwave resonator disposed adjacent the dielectric coating and having a resonance frequency with an operating bandwidth about the magnetic resonance of the nitrogen vacancy centre, the resonator having a suppressed portion and an unsuppressed portion wherein the field generated by the unsuppressed portion is greater than the field of the suppressed portion;
• an optical filter disposed adjacent the microwave generator;
• at least one sensor photodiode array disposed adjacent the optical filter and aligned with the unsuppressed portion of the microwave resonator;
• and
• at least one reference photodiode array spaced apart from and substantially in the same plane as the sensor photodiode, the reference photodiode being aligned with the suppressed portion of the microwave resonator.